Charging in a warm or hot enclosed space, like a garage

[Focused_Driver]

We had our first pretty warm consecutive days in the Pacific NW this week since owning my FFE. When plugging in to charge I experienced some new sounds and things, like cooling fans turning on- which were a lot louder than I was expecting. The fan speed varied up and down multiple times through the full charge cycle as I'm sure the temperature of various things in the system changed and was being regulated. Multiple times I could hear the sound of the fan(s) blowing from inside my house through the insulated door. Understanding that the charging process is going to generate heat, I'm glad to hear all the battery temperature management hardware is working to keep the battery temperatures regulated, but I still have a concern.

My garage, as I would expect for most, is not climate controlled and has only one small vent to allow airflow in for my natural gas furnace and hot water heater. In the summertime the temperature inside my garage can get pretty warm, especially after mid-day when the sun starts beating down on my west facing garage doors. I don't recall how warm it gets but I am pretty certain temperatures above 80 degrees are pretty common and in the 90s are likely.

Is there an ambient temperature, within an enclosed space, at which I should be concerned that the FFE's battery temperature management system won't be able to keep the batteries cool enough? I noticed quite warm air coming off of the FFE during charging that will continue to warm the ambient air in my garage.

Does the cooling system simply circulate fluid through the battery and a simple heat exchanger to reduce the heat in the batteries using ambient air, or does it actually use some kind of refrigeration process to extract heat from the fluid circulating through the batteries? It all just looks like simple coolant, pumps and fans to me.

 

[markminnc]

I live in SE NC and our summer temps are much higher than yours, not much cool down at night. I charge almost every night, I have the chg set to begin at midnight. I am normally sleeping as the car charges, but occationally I have heard the cooling fan come onduring a chg. I have been doing this for 14 months without issue.

 

[vivavegas]

I live in Vegas, and I've had my focus out in 118 degree weather, and the fans come on fast and loud when pulling in and charging after driving all day. And still have had no problems with my focus, runs just like when I bought it. (14,000 miles on it now).

 

[WattsUp]

Does the cooling system simply circulate fluid through the battery and a simple heat exchanger to reduce the heat in the batteries using ambient air, or does it actually use some kind of refrigeration process to extract heat from the fluid circulating through the batteries? It all just looks like simple coolant, pumps and fans to me.

Supposedly the car does use a chiller to cool the fluid (the same one used for A/C).

 

[michael]

As best I can tell that's correct...has active cooling. The limitation is that the system is not aggressive, and appears not to cool the battery below approximately 96-98 F. So on very hot days it surely helps, but in moderate weather it doesn't appear to be active.

I believe we don't know much about the specific battery chemistry and what constitutes an unreasonably high temperature. The batteries in the ill-fated Leaf have been demonstrated to be particularly intolerant of high temperatures compared, for example, to the batteries in a Tesla. Our batteries may be very happy at 98 F, I don't know...

 

[v_traveller]

I've had the TMS come on during charging when it was 80-85F ambient, while stuffing that last kWh into the battery, both during L1 and L2 charging. L1 seems to just run a circulation pump, and at L2 much more is happening, at least audibly (fans running). I have some screen captures from chargepoint that show the TMS apparently drawing a lot of current, will dig them up and post later... seems the TMS is drawing 3-5kW at L2, so I'd imagine that there is more than just a coolant pump and fans running.

 

[WetEV]

I believe we don't know much about the specific battery chemistry and what constitutes an unreasonably high temperature. The batteries in the ill-fated Leaf have been demonstrated to be particularly intolerant of high temperatures compared, for example, to the batteries in a Tesla. Our batteries may be very happy at 98 F, I don't know...

Battery life probably follows Arrhenius equation. http://en.wikipedia.org/wiki/Arrhenius_equation

the reaction rate doubles for every 10 degree Celsius increase in temperature.

Or in other words, if a battery lives for 11.4 years in Juneau, AK, will live for 2.5 years Phoenix (without active cooling).

http://electricvehiclewiki.com/Battery_Capacity_Loss

Models of battery life show large gains in battery life for active cooling over passive airflow in hot areas and much smaller gains in moderate areas, and no gain (or even a small loss) in battery life in cooler areas.

Leafs in the Pacific Northwest are hardly "ill-fated". But if I lived in Vegas, I'd bought a FFE rather than a Leaf.

 

[EVA]

Michael - not sure if it is the batteries that are heat tolerant (I would guess they are all equally affected by heat). The Leaf does not have active temperature management for the batteries. The FFE and Tesla both have active temperature management (the Tesla batteries would never survive supercharging if there wasn't active cooling).